Using in operando impedance spectroscopy technique to unravel the sintering process evolution of Bi2O3:LATP cold-sintered solid electrolyte

Abstract

A NASICON-type Li1+xAlxTi2-x(PO4)3 (LATP) cold-sintered solid electrolyte is reported with a dense structure, as a possible alternative the commonly recognized liquid organic electrolytes. A low-temperature sintering technology (below 200 °C) with a sintering additive, aid of acid solvent and high pressure is originally developed for preparing the solid electrolyte. In addition, the setup has been designed using in operando impedance technique simultaneously, the Cold Sintering Process (CSP) is monitored in order to explore the mechanism are taking place during the densification. As a result, an ionic conductivity as high as 4.48·10−5 S·cm−1, with a relative density of ∼82% has been achieved for 2 wt% Bi2O3 and 25 wt% 3 M acid acetic solution, LATP powder, and sintered under 700 MPa and at 150 °C, reaching the highest value in published peer-reviewed literature. The cold-sintered ceramics without post-annealing high temperature treatments present kinetics limitations due to intergranular regions. Therefore, this bottleneck must be studied and overcome to achieve higher ionic conductivities at low temperatures.